Yield Modeling of Rectangular Defect Outline

In integrated circuits, the defects associated with photolithography are assumed to be in the shape of circular discs in order to perform the estimation of yield and fault analysis. However,real defects exhibit a great variety of shapes. In this paper,a novel yield model is presented and the critical area model of short circuit is correspondingly provided. In comparison with the circular model corrently available, the new model takes the similarity shape to an original defect, the two-dimensional distributional characteristic of defects, the feature of a layout routing and the character of yield estimation into account. As for the aspect of prediction of yield, the experimental results show that the new model may predict the yield caused by real defects more accurately than the circular model does. It is significant that the yield is accurately estimated and improved using the proposed model.

Mechanism and Improvement of Straight Edge Seam Defect on Hot-rolled Plate Surfaces through Use of Chamfered Slabs

To improve the straight edge seam defect on hot-rolled steel plates,the deformation and temperature distribution of rectangular slabs and chamfered slabs during rolling in a pilot rolling experiment were analyzed in detail using the finite element method.The results showed that the crease formed on the lateral side near the edge of the plate as a result of uneven stress during broadside rolling.The creases rose to the surface with unrestricted spread and evolved into a straight edge seam during the subsequent straight rolling.To eliminate the straight edge seam defect,chamfered slabs were developed and investigated for rolling.The use of the chamfered slabs provided two advantages for rolling：the distribution of the temperature near the edge was ameliorated,and the deformation shape was improved by the chamfered shape.As a result,the risk of forming a straight edge seam defect was reduced by the use of a chamfered slab.